WO 2012068692 A1 describes an apparatus for compaction of a fiber material on a spinning machine, which is provided for the subsequent addition onto a conventional drawing mill device of a spinning machine. The apparatus is disposed downstream from the drawing mill unit of the spinning machine and serves to compact a fiber material discharged from the drawing mill unit. Following the compaction apparatus, the compacted fiber material, after passing through a pinch point, is sent to a twist-creating device. The twist-creating device consists of a rotor, for example, which revolves on a ring in the case of a ring-spinning machine, for example, wherein the yarn thereby produced is wound onto a rotating sleeve.
For use on the usual twin drawing mills of ring-spinning machines, the compaction apparatus described in WO 2012068692 A1 has two driven and rotating suction drums, which are acted upon by suction air and are rotatably mounted, so that they are axially parallel to one another and spaced a distance apart from one another by means of a bearing element on a shaft mounted on a carrier. The carrier has a receptacle for rotationally fixed mounting of the shaft. To axially secure the suction drums on the shaft, a sleeve-type locking element is described in WO 2014027234, this locking element being pushed onto the end section of the shaft and/or the shaft journal. Thus, two suction drums as a unit (module) are assigned to a twin drawing mill. The carrier has a suction channel connected to a vacuum source, also connected to the interior space of the suction drum by means of corresponding inserts. The inserts are provided with suitably shaped suction slots, so that a corresponding air flow is created at the periphery of the respective drum in a compaction area. Due to this air flow, which is directed essentially transversely to the direction of transport of the fiber material, protruding fibers are also bound into the fiber material.
A ring-shaped drive element in the form of a friction wheel, which is partially in contact with the circular peripheral surface of a shoulder disposed on the end side of the respective suction drum, is in contact along its circular inside surface under the action of a pressure load. The rotational movement of the friction wheel driven over the outside circumference, which is connected to the suction drum, is transferred by means of friction to the circumferential surface of the shoulder. The friction wheel in turn is driven by fiction-locking connection by the driven lower output roller of the drawing mill. Due to a sealing cap attached to the end of the shoulder, the friction wheel is held in its position in the axial direction on the shoulder, so that an axial gap is formed between the closed end side of the suction drum and the friction wheel.
During the compaction process, individual fibers may become detached from the fiber material to be compacted and may be deposited in the interior of the suction drum. This can lead to blockage of the suction slot, so that compaction of the fiber sliver is no longer ensured. Furthermore, fibers may be deposited on the circumference of the suction drum and enter the axial gap between the closed end side of the side of the suction drum and the friction wheel. There is the risk here that fibers entering the axial gap may continue to move as far as the outside circumference of the shoulder and become attached there. The result here is that the inside surface of the friction wheel is no longer in direct contact with the outside circumference of the shoulder, so that continuous transfer of the driving torque from the friction wheel to the suction drum is no longer ensured. As a result, the speed ratio between the suction drum and the lower output roller of the drawing mill changes. This causes initial compression of the fiber material to be compacted in the compaction area, which in turn has a negative effect on the quality of the compaction of the fiber material.
Based on the problems described here, there is therefore the need to remove the suction drum from the carrier after a certain running time of the compaction apparatus and then to free the suction drum of the accumulated fibers. In doing so, the suction drum is pulled jointly with the bearing element pressed into it from the shaft journal by the operator, cleaned outside of the apparatus and placed back on the shaft journal. An important disadvantage is that, after frequent assembly and disassembly of the suction drum, rust due to friction develops on the outside surface of the shaft journal and the inside surface of the bearing element. Therefore, simple and rapid assembly and disassembly of the suction drum are no longer ensured after a longer running time of the apparatus. This has a negative effect on the maintenance cost of the spinning machine.